code: def create_data_mmap(self):
      for dataset in self.datasets:
          dataset.create_data_mmap()
  
file_path: NeMo/nemo/collections/nlp/data/language_modeling/megatron/blendable_dataset.py
imports: import time
  import numpy
  import torch
  from nemo.utils import logging
  from nemo.utils.app_state import AppState
label_desc: Use image node_id 4 for calling the BlendableDataset obj's underlying member method code with example usage: obj.create_data_mmap() without return types